A reporter was recently trying to calculate how many people were employed by startups funded by Y Combinator. His back of the envelope estimate was 200, which seemed high to me, so I asked all the startups.
It turned out he was dead on. There are now 26 YC-funded startups that have employees other than the founders, and between them they employ 198 people.
If you're a great Rails hacker, you could make that 199: http://www.airbnb.com/home/jobs